It's a very powerful and functional program. But it's not a very good looking one. Given its price and the power, that's not a huge issue for me personally. But there are a lot of people who would not use it simply based on how it looks. Anything you can do to make it look less like something released during the Windows 98 era would probably be a step in the right direction.

technical questions about SVG you should ask technical people like me ant not designers and artists.

AFAIK svg can be rendered by external libraries like batik which we already use in a svg plugin and a much smaller smaller (only 300 KB jar file) svgsalamander https://svgsalamander.java.net/I have no idea about performance but it can always be solved using caching. It means given the icons and spending some moderate efforts we should be able to have svg icons too.

Yes that would be really great. We have a cool splash screen now but the rest is still very old fashioned. I'm afraid that the main issue with Freeplane is usability which only partly can be fixed by better graphics but they would be a good start.

making SVG versions of pixel icons can be a great task. maybe there is a swap option where you can setup the mindmap it self for scalalbe icons. other users which dont need it can avoid then a performance change.

usability depends much on the user. i avoid using mouse at all cost. i do all stuff with keyboard shortcuts. a great feature would be to navigate through first letters of nodes but i didnt tried to request it yet. i dont like over bulked ui with big graphics, this trend comes to so many places. fast accessible list view with improved keyboard navigation would be great.A idea could be to make different "themes" one for annuitant people with win8 like tiling and some dynamic resizeable stuff for others .Greetings

Hello,all the icons that are now used in Freeplane I originally made ​​in Inkscape,So all icons are in svg format, if you want I can send to you all my work in svg format.You can change them or replace with new one.